Surface treatment of Die Casting aluminum
Casting is a process of metal smelting and processing, which usually uses the gravity of metal to cast in the mold. However, “aluminum die-casting” is not completed by gravity, but by exerting a certain pressure. It is similar to “injection molding”. But it has a set of core pulling and cooling systems with high technical content. In general, the materials are sent to the cavity to be cast through a centralized inlet to form parts.Die casting usually used for precision instrument or sealing case.
Today we mainly introduce the surface treatment of die casting aluminum parts or case.As we known,there’re several treatments for aluminum alloy.
- Powder coating,the powder coating is sprayed on the surface of the die casting to make its electrostatic effect only adhere to the surface of the workpiece, so the die casting aluminum has good corrosion resistance and aging resistance.
- Baking process, it is first coated with aluminum alloy after phosphating, and then baked the surface of die-casting aluminum parts after spraying. In this way, the sprayed coating has outstanding corrosion resistance and bright wear resistance functions.
- Fuel injection, this surface treatment is a general term for the current industrial commodity surface spraying processing, which can effectively make its products have the functions of conflict resistance, UV resistance, etc.
- Anodizing.The anodizing we are talking about is generally anodic oxidation. anodizing is the process of forming a layer of oxide film on aluminum products (anodes) under the action of external current under the corresponding electrolyte and specific process conditions.
There has always been a dispute in the industry as to whether die-casting aluminum parts can be anodized. So today we will discuss whether die-casting aluminum can be anodized?
In fact, whether die-casting aluminum can be oxidized depends on the aluminum alloy materials used for die-casting. We know that the main components of aluminum alloy are aluminum, magnesium and silicon. The most important one is the content of silicon element, which must not be greater than 12%, because silicon element is an inert element, and anodized relies on the chemical reaction of acid and aluminum alloy to form an oxide film on the surface. Anodizing requires that the aluminum surface is free of impurities, and the aluminum material is relatively pure, because the anodizing film must be uniform and flat. Excessive impurities and other components will inevitably affect the thickness of the film formed during anodizing, and even directly affect whether the film is formed. Most importantly, other metal elements may directly change the color of the anodic oxide film when it is formed. If the silicon content is high, the anodic oxide film may be dark even if the special dust remover for die casting aluminum is used, and it is difficult to obtain a colorless and transparent oxide film. With the increase of silicon content, the color of the anodic oxide film will change from light gray to dark gray to black gray. This is why most people say that die-casting aluminum parts are not suitable for oxidation treatment. However, if the material is changed and the content of silicon element is reduced, anodizing can still be carried out.
98% aluminum die-casting products can be made into aluminum natural color, bright silver and various colors. About 90% of die-casting aluminum products can be made into dark colors such as dark gray, dark brown and black. Conductive oxidation with sulfuric acid, with uniform and bright surface color. 98% aluminum die-casting products can be made into aluminum natural color, bright silver and various colors. About 90% of die-casting aluminum products can be made into dark colors such as dark gray, dark brown and black. Conductive oxidation with sulfuric acid, with uniform and bright surface color.
In fact, the surface treatment of die-casting aluminum by powder spraying or oil spraying can not only achieve beautiful external surface, corrosion resistance and wear resistance, but also save costs. It is unnecessary to use anodized treatment all the time.
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